The present invention relates to a window which is installed in an outdoor opening of a building, and more particularly, to an outdoor window having an approximately flat top surface on a sill. This window is superior in drainage from the flat top surface and is superior in airtightness and watertightness on an indoor side even during a rain storm when the top surface on the sill is formed to be flat.
A barrier free structure in which steps are eliminated from the doorways of rooms and the doorway of a bathroom in a house or the like is publicly known.
However, in the case where a window which is installed in an outdoor opening of a building is formed as a merely flat structure in which projecting rails are eliminated from the top surface of an existing projecting-rail type of sill (refer to FIG. 20) to simply eliminate steps which would have been disposed in the direction in which a person goes in or out, there is a high risk that a large amount of rainwater which blows on a sliding sash or the like under a large wind pressure during a rain storm flows onto that flat surface and rainwater enters an indoor side together with a flow of wind. On the other hand, in the case where a groove is provided on the flat surface of a sill and a large drain space is provided below the groove, it is impossible to ensure strength and rigidity enough to support the weight of a door or the weight of a person who goes in and out. In addition, very strict quality standards are specified under Japanese Industrial Standards. For example, the quality standard of an outdoor opening window that is specified under Japanese Industrial Standards is very strict as follows: at a test class of 50 grades, water is not allowed to leak into an indoor side when water is sprayed at a rate of 4 liters/square meter per minute while a wind pressure is being applied in the form of a pulsating pressure which is a maximum of 750 Pa and a minimum of 250 Pa and an average pressure difference of 500 Pa (this test will be hereinafter referred to a 500-Pa grade test). Therefore, a barrier free outdoor opening has been considered to be difficult to realize.
For example, Japanese Utility Model Application Laid-Open No. 3-68285 discloses an example in which the top surface of the sill (a portion on which double sliding sashes run) of a window is formed to be approximately flat. This example merely aims at airtightness, and its constituent requirement is that tight materials be provided on the opposite sides of a projecting portion. As a result, the manipulating force required to move a sliding sash is increased by the resistance of the tight materials provided on the opposite sides, and in addition, since the tight materials provided on the opposite sides of the projecting portion hinder outside air from entering a groove in the sill, the difference between the pressure of outside air and the pressure of the groove portion of the sill becomes large, so that it is difficult to realize stable sealing along the entire length of the projecting portion. This leads to the technical problem that owing to such pressure difference, rainwater concentratively flows through a weakly sealed portion and enters an indoor side.
In addition, Japanese Patent Application Laid-Open No. 2000-96934 discloses an example in which a sill is formed to have a flat top surface from which projecting rails are eliminated, and a guide groove is provided on the top surface and a guide plate is extended vertically downwardly from the body of a fitting and is inserted in this groove (1).
However, the fact that the guide plate is tightly engaged with one peripheral end of the guide groove by using a C-shaped bottom guide with a C-shaped rubber (10) aims at the same advantage as the above-cited Japanese Utility Model Application Laid-Open No. 3-68285 in which the tight materials are disposed in contact with the opposite sides of the projecting portion. This fact leads to the technical problem that sliding manipulability is inferior and rainwater stored in the bottom guide enters an indoor side owing to a capillary phenomenon and the pressure difference between outside air and the indoor side.
In addition, since a drain passage is only disclosed as a mere idea, it is impossible to obtain strength enough to support the weight of a door and the weight of a person who goes in and out.